1. Field of the Invention
The present invention relates to a method and apparatus for allocating resources in a wireless communication system and a system thereof. More particularly, the present invention relates to a method and apparatus for allocating resources in a wireless communication system using a persistent scheduling scheme and a system thereof.
2. Description of the Related Art
Next-generation communication systems are being developed to provide various high-speed, high-capacity services to Mobile Stations (MSs). Next-generation communication systems recently discussed include an Institute of Electrical and Electronics Engineers (IEEE) 802.16 communication system and a Mobile Worldwide Interoperability for Microwave Access (WiMAX) communication system. The Mobile WiMAX communication system is a communication system based on the IEEE 802.16 communication system.
With reference to FIG. 1, a description will now be made of a method for allocating DownLink (DL) resources using a persistent scheduling scheme in an IEEE 802.16 communication system.
FIG. 1 is a diagram schematically illustrating a method for allocating DL resources using a persistent scheduling scheme in an IEEE 802.16 communication system.
Referring to FIG. 1, a Base Station (BS) allocates persistent resources 120 of a Hybrid Automatic Repeat Request (HARQ) region 100 to an arbitrary MS, e.g., MS1, using a persistent scheduling scheme. After allocating the persistent resources 120 to the MS1, the BS transmits resource allocation information for the persistent resources 120 to the MS1 using a DL MAP message including a Persistent HARQ DL MAP Information Element (IE).
The Persistent HARQ DL MAP IE includes HARQ region definition information of the HARQ region 100, a Persistent Region Identifier (ID) for identifying the HARQ region 100, a slot offset, and duration information. The HARQ region definition information includes an Orthogonal Frequency Division Multiple Access (OFDMA) symbol offset, a subchannel offset, the number of OFDMA symbols, and the number of subchannels.
The HARQ region 100 is defined by the OFDMA symbol offset, the subchannel offset, the number of OFDMA symbols, and the number of subchannels. That is, the HARQ region 100 represents a two-dimensional region occupied by OFDMA symbols corresponding to the number of OFDMA symbols and subchannels corresponding to the number of subchannels on the basis of a start region 110. The start region 110 represents a region corresponding to the lowest-numbered OFDMA symbol in the lowest-numbered subchannel of the HARQ region 100, and it will be assumed to be, for example, a slot. In addition, the persistent resources 120 include the slots that correspond to information on the duration from the location that is spaced apart from the start region 110 by slots, the number of which corresponds to the slot offset.
With reference to FIG. 2, a description will now be made of a method for allocating UpLink (UL) resources using the persistent scheduling scheme in an IEEE 802.16 communication system.
FIG. 2 is a diagram schematically illustrating a method for allocating UL resources using a persistent scheduling scheme in an IEEE 802.16 communication system.
Referring to FIG. 2, a BS allocates persistent resources 220 to an arbitrary MS, e.g., MS1, using the persistent scheduling scheme in a start region 210 of a HARQ region. After allocating the persistent resources 220 to the MS1, the BS transmits resource allocation information for the persistent resources 220 to the MS1 using a UL MAP message including a Persistent HARQ UL MAP IE.
The Persistent HARQ UL MAP IE includes HARQ region definition information, a Persistent Region ID for identifying the HARQ region, a slot offset, and duration information. The HARQ region definition information includes an OFDMA symbol offset and a subchannel offset. The HARQ region is defined by the OFDMA symbol offset and the subchannel offset. That is, in the UL, unlike in the DL, since the HARQ region is defined not in two dimensions, but in one dimension, the HARQ region is defined in one dimension beginning from the start region 210. The start region 210 represents a slot corresponding to the lowest-numbered OFDMA symbol in the lowest-numbered subchannel of the HARQ region. In addition, the persistent resources 220 include the slots that correspond to information on the duration from the location that is spaced apart from the start region 210 by slots, the number of which corresponds to the slot offset.
Resources allocated to an MS using the persistent scheduling scheme are persistently maintained without being changed every periodic frame, e.g., every P frames, unless the BS releases the resource allocation for the MS or changes the resources allocated to the MS. However, the IEEE 802.16e communication system can variably manage the location of the HARQ region every frame. When the location of the HARQ region is changed in this way, it may be difficult to persistently allocate resources using the persistent scheduling scheme.